I started feeding cereal at 6 months, because I thought the longer she just got breast milk, the better, within reason, and because she was a butterball.
Something I found very useful, healthy and thrifty was to take rolled oats or brown rice and put a tablespoon or two of the dry grains in the blender, or you could use a clean coffee grinder and grind to a fine powder. Then I would mix this with cold water 2:1 and heat/stir until it was cooked. It didn't take long because it was so finely ground. I also used whole grain corn meal, I think.
This way, it was just the whole (organic?) grain, no salt, sugar, wierd stabilizers, preservatives, yadiyah. I didn't spend any extra money on special baby products. I felt good about what I was feeding her.
I also used a little food mill so I could make normal food into baby food so I didn't buy that either. Bananas, vegetables, whatever, it just went in there. Sometimes I put the cooked rice cereal in there with a soaked prune or a chunk of banana too. As she got older I added wheat germ, cottage cheese, etc. etc.
My daughter is 19 now, so the memories are dim, but I remember these were some of the ideas I had that I really liked.